I took this from a moving vehicle this afternoon, so apologies for the poor resolution. This is in Athena, Oregon, and it is not a Thunderbeam. The motor is at the bottom and there is some kind of intake tube on top. Some kind of HOR, maybe?
Their main siren downtown appears to be a single-tone Banshee, but I couldn't get a shot or get close enough since I wasn't driving.
By the way, I heard my very first SD-10 today, the noon signal in Pendleton.